Sulphurized dihydro polycyclic aromatic hydrocarbons and process for making same



This invention relates to sulphurized dihydro SULPHURIZEll DIHYDRO POLYCYCLIC ARO- MAI'IO. HYDBOCARBONS AND PROCESS FOR SAME I Paul La Frone Magill, Ransomviile, N. Y., as-

signor to E. I. du Pont de Nemours & Comp y, Wilmington, Del., a corporation oi Delaware No Drawing. Application July 29,4987,

' Serial No. 156,424

Claims. (01. 260-139) cooling to room temperature. In general, the

polycyclic aromatic hydrocarbons, to their preparation and to the use of these'products as lubri; cant assistants in lubricating compositions.

5 One objectof this invention is to, provide a.

method for preparing new dihydro polycyclic aromatic hydrocarbon-sulphur reaction products. A further object is tc pro'vide improved lubricating compositions which contain the above sulphur- ]0 ized products as lubricant assistants and top'ro- 1 vide a method for incorporating such products into lubricating compositions such as cutting oils, extreme pressure lubricants and the like. Other objects will be apparent from the ensuing description of my-invention.

Theabove' objects may be accomplished in accordance with my invention by heating a dihydro polycyclic aromatichydrocarbon or a homologue thereof with sulphur to form a sulphurreaction product or said dihydrocarbon and, when it is desired to employ the product as a lubricant assistant, incorporating the product into alubricating oil.

p I have discovered that sulphur may be reacted :5 with dihydro polycyclic aromatic hydrocarbons or their homologues. g., the alkyl derivatives of such dihydro hydrocarbons, to give products 7 which appear to be definite compounds, although themature oi the reaction involved and the exact identity ofthe products formed are not-entirely understood. In the specification and in .the appended claims, I use the term' dihydro polycyclic aromatic hydrocarbons? .to include those polycyclic hydrocarbons and their homologues whose molecular structures includes a benzene nucleus in addition to a. partially hydrogenated carbon mic reaction takes place to produce a straw col.-

ored, clear oil, the molecular weight 01' which in general increases as the sulphur content increases. The'reaction occurs substantially without hydrogen sulphide evolution, which distinguishes it from the reaction of sulphur with aliphatic compounds. The maximum amount of sulphur that may bereacted with dihydronaphthalene is limited in that when the reaction product contains more than 25-26% of sulphur, un-

' s reacted sulphur separates from the mixtureon molecular weight of the product is approximately 260 when the maximum amount of sulphur is contained therein.

The dihydronaphthalene which is most'suitable for preparing the present sulphur product is 1,4- dihydronaphthalene. The 1,2-dihydronaphthalene' may also be employed with good results; however; this hydrocarbon is not as readily obtainable as isthe 1,4-dihydro compound. The dihydronaphthalene which I prefer to employ UNrrEo STATES PATENT. OFFICE i" may be readily prepared by the method which is Y I objectionable.

The dihydro derivatives of other polycyclic aro-. matic hydrocarbons or their homologues, in gem eral, may also be prepared by the method described in the above patent for the preparation of dihydronaphthalenej However, my inventionv is not limited to the use of compounds prepared by the method of this patent, since any dihydro polycyclic aromatic hydrocarbon or its homologues, regardless-of its method of preparation.

may be employed with excellent results. The preparation of the sulphurized dihydro hydrocarbons of my invention is illustrated by the is employed.- a Example A mixture or sulphur and dihydronaphthalene following example wherein dihydronaphthalene (principally the 1,4-dihydro compound containing about 20% of naphthalene as'an impurity) in the proportion of one mol of dihydronaphthaleneto one atom of sulphur was heated in a nitrogen atmosphere during constant agitation. As the temperature reached approximately 0., an;

exothermic reaction took place. The heating was continued for 1 hours at C. and thereafter the mixture was cooled to room temperature when the naphthalene impurity precipitated and was filtered out. The product obtained was a straw colored,.clar oilcontaining 24% of sul- In a similar run, twice the amount of sulphur was employed and the unreacted sulphur was separated from the mixture by dissolving the reaction mixture in petroleum ether. The product separated from the petroleum ether fraction contained 23.9% of sulphur and had a molecular weight of 244. Apparently the sulphur forms a true compound with the hydrocarbon since I have found that the molecular weight of the reaction product increases as the sulphur content is increased. However, products containing more than 25-26% of sulphur may not be obtained since the excess sulphur separates from the product upon standing.

My invention is not limited to the use of specific proportions of sulphur and the dihydro hydrocarbon in preparing the sulphurized product. However, there is generally no advantage in employing sulphur in quantities greater than that required to give a reaction product containing more than 2526% by weight of sulphur since sulphur in excess of this amount precipitates from the product. The use of one atomic proportion of sulphur to 0.7 to 2.5 molecularproportions of the dihydro polycyclic aromatic hydrocarbon is generally preferred since under such circumstances substantially all of the sulphur is reacted. Thus, by reacting one atom of sulphur with 0.7 mole of dihydronaphthalene, a product containing 25-26% sulphur is obtained. If the proportion of dihydronaphthalene is increased to 2.5 moles per one atom of sulphur, the resulting product will contain about 8.9% of sulphur.

If desired, the reaction product may be isolated by distillation under reduced pressures, e. g. 4 mm. Also, sulphur which is unreacted but merely dissolved in the reaction product may be removed therefrom by treatment with a solvent, e. g,. petroleum ether, in which sulphur is insoluble, so as to separate the unreacted sulphur, the desired product being' separated by distillation from its solution in the solvent. However, for most purposes for which the product may be used, the presence of impurities such as unreacted sulphur is not objectionable and purification of the reaction mixture by the above or other methodsis not necessary.

The rate of reaction between sulphur and the dihydro hydrocarbon usually is not sufliciently rapid at temperatures substantially below C. for practical purposes. On the other hand, control of the reaction, which is exothermic, at temperatures in excess of about C. is difficult. It is therefore preferred to. efiect the reaction at a temperature of about 140-170 C. However, by employing reaction mixtures which are diluted by inert solvents, it may be possible to carry out the reaction in accordancewith my invention at temperatures in excess of 170 C. Control of the rate of reaction may also be facilitated by heating the dihydro polycyclic aromatic hydrocarbon to the desired reaction temperature, e. g., by means of an oil bath, and then adding the sulphur thereto in small increments. It will be understood that the above stated optimum reaction temperatures are approximate and will vary more or less for different hydrocarbons employed. In most cases, however, I prefer to employ a reaction temperature of 140 to 170 C.

'One important characteristic of my sulphurized hydrocarbons is that they are homogeneous mono-phase liquids, i. e., they contain no suspended solid or other materials. Thus the dihydronaphthalene-sulphur reaction product is a strawcolored clear oil.

My sulphurized hydrocarbons are soluble in various organic solvents and particularly the hydrocarbon solvents and their chlorinated products. Thus, they are soluble in petroleum and vegetable oils, the ordinary chlorinated hydrocarbon solvents, benzene, toluene, waxes and greases and the like. Because the products are clear liquids and are readily soluble in numerous solvents, they are of potential value for many purposes where sulphur or sulphurized products are required. In particular, I have found that these products are well'suited for use as lubricant assistants in lubricating compositions such as cutting oils, high pressure lubricants, greases and the like.

The products are particularly suitable for use in cutting oils since they not only appreciably increase and improve the lubricating properties of the compositions but also are easily miscible with the oil base to give clear compositions which are generally desired for cutting oils. By means of my invention, relatively large amounts of sulphur may be added to a cutting oil without darkening the same. This is an important advantage, since light colored, transparent oils are essential for r cutting oil applications. The amount of the sulphurized product, e. g., the reaction product of .dihydronaphthalene and sulphur, that need be added to the oil will vary with the use for which the oil is intended. In general, I find it suitable greases and the like is known to increase the load I capacity of the composition. I have discovered that the sulphurized products of dihydro polycyclic aromatic hydrocarbons whose preparation has been described and illustrated above are excellent sources of sulphur for use in such lubricating compositions. Thus, the dihydronaphthalene-sulphur reaction product which contains from 20 to 25% sulphur may be added to a gear oil so as to product a sulphur content from 1 3% and under such circumstances the load carrying capacity of the gear oil is markedly increased.

My invention is not limited to the addition of the above sulphurized products'to oils of any particular viscosity, nor to hydrocarbon woils, since such compositions maybe added to high or low viscosity mineral oils, including greases, as well as to oils of vegetable origin with excellent results.

Because my sulphurized dihydronaphthalene is a liquid at ordinary temperature, it may be easily incorporated in any desired amount into cutting oils or extreme pressure lubricating compositions and the like. If the composition into which it is to be incorporated is relatively viscous at ordinary temperature, it is best to heat the composition so as to facilitate thorough dispersion of the sulphur product therein.

It is to be understood that that-modification of my invention which relates to the use of the present sulphurized products as lubricant assistants "is not limited to the particular concentrations mentioned above as illustrative since the.

any desired sulphur content within wide limits since they are readily miscible with the base materials of such compositions.

In the foregoing, I have described the preferred .embodiments of my invention and various modifications thereof. It is to be understood that the present invention is not, to be limited to such embodiments since they are merely illustrative sulphurized products may be employed to give and not restrictive of my invention. My invention .is to be limited only by the. scope oi. the appended claims.

In the appended claims, the term lubricating compositions" is used to designate oleaginouscompositions in general which have'lubricating properties, regardless of whetherthe lubricating base is of mineral or vegetable origin. It also designates compositions of ,high or low viscosity,

including, for example, cutting oils, light lubricating oils, e'xtreme pressure lubricating compositions, greases and the like. The term lubricating oil is used to designate any solid or liquid substance of either mineral or vegetable origin which has recognized lubricating properties. Cutting oils are special lubricants used to lubricate and cool various cutting tools in machine tools such as lathes, milling machines and the like.

Iclaimz 41. A process comprising reacting a dihydro polycyclic aromatic hydrocarbon .with sulphur 3. A process comprising heating a dihydro polycyclic aromatic hydrocarbon with sulphur in the proportion of about'0.'l-2.5 mole of said dihydro polycyclic aromatic hydrocarbon to one atom of sulphur at a temperature of about 140-170 0.,

-- double bond.

said hydrocarbon having a molecular structure which includesa benzene nucleus in addition to a partially hydrogenated carbon ringcontaining at least one double bond.

4. A process comprising reacting dihydronaphthalene with sulphur between the temperature at which sulphurization begins and that at which evolution of hydrogen sulphide becomes appreciable.

- 5. A process comprising heating dihydronaphthalene with sulphur at a temperature" 01 about 140-170 C.

6. A process comprising heating dihydronaphthalene with sulphur in the proportion of about 0.7-2.5 mols of dlhydronaphthalene to one atom of sulphur at a temperature of about 140-170' C.

'I. A composition of. matter comprising essentially a homogenous, mono-phase, liquid reaction product 01 a dihydro polycyclic aromatic hydrocarbon and sulphur, said hydrocarbon having a molecular structure which includes a benzene nucleus in addition to a partially hydrogenated carbon ring containing'at least one double bond. 8. A composition of matter comprising essentially a homogeneous, mono-phase, liquid reaction product of a dihydro polycyclic aromatic hydrocarbon and sulphur containing from about 8.5 to 26% of sulphur by weight, said hydrocarbon having a molecular structure which includes a benzene nucleus in addition to a partially hydrogenated carbon .ring containing at least one 9 A composition or matter co'mpri'sing a homogeneous, mono-phase, liquid reaction product of dihydronaphthalene and sulphur.

' 10. A composition of matter comprising a homogeneous, mono-phase, liquid reaction product of dihydronaphthalene and sulphur containing from about 8.9 to 26% of sulphur by weight.

PAUL FRONE' MAGIIL. 

